The proposed research will confirm and extend previous work indicating that frontal lobe maturation underlies many of the important cognitive advances of the first years of life. The present set of experiments will focus on two fundamental cognitive skills known to be subserved by the frontal lobe: relating information over a temporal or spatial separation and inhibiting predominant action tendencies. Infants ranging in age from 6-18 months will be tested on 5 tasks directly linked to frontal lobe function. The research will chart the precise developmental progression for acquisition of the relational and inhibitory abilities required by these tasks. This work will provide a bridge beteen two previously disparate but highly complementary fields of inquiry, developmental psychology and the neurobiology of cognition. Its results will have important theoretical, practical, and clinical implications: (1) They should yield new interpretations of the what is developing during the first years based on our knowledge of frontal lobe function. (2) By delineating developmental sequences through which all children progress the proposed research should ease parental concerns and provide guidance for educators in the design of pedagogical practices. (3) Finally, it is hoped that this work will lead to standardized, non-invasive markers for assessing CNS insult and integrity during early development.